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 * (a) the Software, and
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 * (b) any piece of software and/or hardware listed in the lrgrwrks.txt file if
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package com.oracle.graal.python.builtins.objects.cell;

import com.oracle.graal.python.builtins.objects.PythonAbstractObject;
import com.oracle.graal.python.util.PythonUtils;
import com.oracle.truffle.api.Assumption;
import com.oracle.truffle.api.CompilerAsserts;
import com.oracle.truffle.api.CompilerDirectives;
import com.oracle.truffle.api.CompilerDirectives.TruffleBoundary;

public final class PCell extends PythonAbstractObject {
    private final Assumption effectivelyFinal;
    private Object ref;

    public PCell(Assumption effectivelyFinalAssumption) {
        this.effectivelyFinal = effectivelyFinalAssumption;
    }

    public static PCell[] toCellArray(Object[] closure) {
        PCell[] cells = new PCell[closure.length];
        PythonUtils.arraycopy(closure, 0, cells, 0, closure.length);
        return cells;
    }

    public Object getRef() {
        return ref;
    }

    public void clearRef(Assumption assumption) {
        setRef(null, assumption);
    }

    public void clearRef() {
        setRef(null);
    }

    @TruffleBoundary
    private static void invalidateAssumption(Assumption assumption) {
        assumption.invalidate();
    }

    public void setRef(Object ref) {
        if (this.ref != null) {
            invalidateAssumption(effectivelyFinal);
        }
        this.ref = ref;
    }

    /**
     * Use this to pass in the effectivelyFinal assumption from a node that made it constant.
     */
    public void setRef(Object ref, Assumption constantAssumption) {
        assert constantAssumption == effectivelyFinal;
        if (constantAssumption.isValid()) {
            if (this.ref != null) {
                invalidateAssumption(constantAssumption);
            }
        }
        this.ref = ref;
    }

    public Assumption isEffectivelyFinalAssumption() {
        return effectivelyFinal;
    }

    @Override
    public String toString() {
        CompilerAsserts.neverPartOfCompilation();
        if (ref == null) {
            return String.format("<cell at %s: empty>", hashCode());
        }
        return String.format("<cell at %s: %s object at %s>", hashCode(), ref.getClass().getSimpleName(), ref.hashCode());
    }

    @Override
    public int compareTo(Object o) {
        CompilerDirectives.transferToInterpreterAndInvalidate();
        throw new UnsupportedOperationException();
    }
}
